Beryllium is a metal that is used in a wide variety of industries including electronics, aerospace, defense, and the Department of Energy (DOE) complex. Exposure to beryllium containing particles can lead to a lung disease called Chronic Beryllium Disease (CBD). CBD involves an uncontrolled immune response in the lungs that can lead to deterioration in breathing capacity and ultimately death. It is clear that even in processes where beryllium dust has been controlled to very low levels, cases of disease still persist. In fact, there have been cases of CBD reported in people that have had no obvious direct contact with beryllium operations. Despite the fact that very low exposure levels can lead to CBD, the onset of disease can take decades.
Recent new regulations from DOE dictate a permissible exposure limit of 0.2 μg/m3 in air, a housekeeping level of 3 μg/100 cm2 on a surface, and a release level for materials after beryllium exposure where the surface contamination due to beryllium must not exceed 0.2 μg/100 cm2. There is a discussion in the beryllium community if the permissible air exposure limit needs to be lowered to 0.02 μg/m3. Currently, thousands of surface wipes and air filters are analyzed annually for beryllium. In addition OSHA has detected airborne levels of beryllium at numerous sites within the United States. The present technique for detecting beryllium is a surface analysis that involves wiping an area with a filter paper, performing a microwave digestion with acid to dissolute beryllium or its compounds, and then analyze by inductively coupled plasma (ICP) atomic emission spectroscopy (AES). For analyzing airborne samples, one draws a known quantity of air through a filtering medium and then it is treated in a similar fashion to the surface wipes. This process can take two days or more and is not readily usable in the field. The ICP-AES technique also requires highly trained operators and the entire sample is consumed in order to meet the detection levels so that a sample that is identified as positive for beryllium cannot be checked or verified with a second run.
Although there are several reports of being able to detect beryllium with a fluorescent indicator (see Matsumiya), only recently quantitative fluorometric beryllium detection methods that have been shown to be effective for the current exposure regulations. Three key elements to a useful detection system that have been missing previously are: first, the detection system must be capable of dissolving both beryllium oxide and beryllium metal; second, the detection system must work in the presence of other metals and fluoride ions. Third, the detection system must be easy to use and preferably offer the ability to be field portable. Most fluorescent indicators reported in literature do not tolerate the presence of fluoride ions, which is critical if a fluoride-based medium is used to dissolve the beryllium. The few reports of fluorescent indicators that can tolerate fluorides, have used complicated procedures involving heating with acid for dissolution and a titration process to obtain the final pH that require long periods of time and prohibit use in the field.
The extensive chemistry required in previous fluorescent systems and interferences from other metals have limited their use, and to date there is no simple approach to beryllium detection by fluorescence. A quick, simple and specific approach has now been developed for the detection and quantification of beryllium as claimed in U.S. patent application Ser. No. 10/812,444 filed on Mar. 30, 2004 and is incorporated herein by reference. Further this method provides a quantitative method of determining beryllium or a compound thereof (including beryllium oxide) in a sample, which has a fast turnaround time and can be made to be readily field portable.
One object of the present invention is to practically enable the method by prolonging the shelf life of the indicator so that practical test kits may be designed which are durable.
Yet another objective of this invention is to use this method to get a particle size distribution of beryllium comprising particles which are airborne.
Another objective of this invention is to increase the sensitivity of the test by tuning the chemistry of the process and thermal control of the sample being measured, in addition it is also beneficial to extend the dynamic range of the measurement.
Yet another objective of this invention is to assist in the dissolution process by changing at least one of the chemistry of dissolution solution and/or influencing the kinetics of dissolution by heat, microwave and ultrasonic treatment for samples to be analyzed by fluorescence.
Another objective of the invention is to provide a highly automated system to analyze several samples with less handling and labor both to reduce cost and increase process safety and consistency.